RIA opiates: structure versus reactivity.

Twenty-six different opiates were analyzed by radioimmunoassay (RIA) at five different concentrations. At attempt is made to relate structural differences to the affinity of the compounds for the Roche RIA morphine antibody. The effects of substituent placement on the morphine molecule are studied. As expected, the basic 5-ring opiate structure is essential for reactivity. Addition of an alkyl group to the oxygen in the 3-position increased affinity, but alteration of other key functional groups had a reverse affect.